"This campaign is designed to help commuters tap into new ways of working. The mobile workforce is constantly growing and, as such, so is the need to access mobile internet," said Microsoft marketing executive Philippa Snare.

"Having free WiFi available is key to this because it enables people to get online quickly and easily as they travel. Simply put, our aim in sponsoring unlimited free WiFi is to ensure users are able to work from anywhere - in the office, at home and in between."

Microsoft launched the initiative to promote its Office 365 subscription package, and will serve users advertising when they connect to the network.

Sky-owned The Cloud will continue to offer Sky News and Sky Sports content, as well as travel information while the promotion runs.

The unlimited WiFi service will be available at selected UK stations until April 24.